I currently own a 1872 also, it's been a really good tractor. I've owned several Cubs with the Magnum engines and they have performed well.
They have two "weak points" that I've experienced. The ignition module requires engine removal to replace, I've done three of those, two on two different 1872's and one on a 1860.
I've also had a carb problem on several Magnums "float sticking?" that allows the crankcase and the cylinders to fill with gas. I was 0 for 2 in carb rebuilds so I sent one off to a Cub dealer for analysis. They rebuilt the carb and a month later the problem returned. You know immediately when this has happenned by the sound of the dead stop in cranking, the cylinder can't compress gas!
Take out a plug, crank her over and it shoots gas at least thirty feet.
But, the 1872 I still own had both of those problems and is aroung 1000 hours, doesn't burn oil and is as strong as ever.
I put a 12v shutoff in line with the fuel supply cuz my tiny brain could't remember to turn the manual on, or off.
Anyway, the 2284 with the 22HP Command is my current primary mower and snow removal tractor. The 551 blower has an improved belt tensioning mechanism but is otherwise the same.
The Commands are WAY more fuel efficient though.
I'll post a couple of pics tomorrow, if my tiny little brain can remember!
Enjoy the day!
Curt